The present invention refers to a mechanism of the type for transferring a rotary motion into an axial motion.
Mechanisms of this type are arranged to transfer a rotary motion into an axial motion when the retainer, which surrounds the shaft is rotated. This retainer hereby will cause rotation of the bearing housings, which are arranged to support bearings, the inner race rings of which enclose and engage the envelope surface of the shaft. The inner race rings during the rotation make a helically sliding motion along the envelope surface of the shaft and if the retainer is kept from moving axially the friction between the shaft and the inner race rings of the bearings will cause the shaft to be exerted to an axial force, which can be used for displacing the shaft. It is of course also possible that the shaft is rotated but prevented from axial movement, whereby the retainer can be displaced axially along the shaft.
Mechanisms of this type are earlier known, see for instance Swedish patent application No. 7415741-3. The bearing housing making part of this mechanism comprises two jaws, which are clamped against each other with appropriate means in such a manner that the inner race rings of the bearings are pressed against a through-shaft. As the bearing seats at this device are arranged in two jaws, which are movable relative to each other the device has a shape which varies with the mutual positions of the jaws, whereby a true circular form of the bearing seats cannot be guaranteed, which means that the bearing race rings easily can be clamped to out-of-roundness with negative influences on the service life of the mechanism and on a smooth running as a result. The jaws are furthermore mutually displaced axially by means of the bearings at axial load on the throughshaft, which furthermore will add to the deformation of the bearing seats when the bearings are heavily loaded.